Bilayer Membranes of Triple-Chain Ammonium Amphiphiles

Ten ammonium amphiphiles which possess three long-chain alkyl tails (C₁₂ or C₁₆) were prepared. They form clear aqueous dispersions upon sonication. Electron microscopy and light scattering experiments indicated the formation of huge bilayer aggregates except for one case. These bilayers undergo the characteristic crystal-to-liquid crystal-phase transition, as confirmed by differential scanning calorimetry (DSC) and by fluorescence depolarization of a diphenylhexatriene probe. Riboflavin, a water-soluble fluorescent probe, was shown to be trapped in bilayer vesicles of some triple-chain amphiphiles. Mixing of these bilayers with those of single-chain and double-chain amphiphiles was examined by DSC and by absorption spectroscopy. Together with our previous results, the present study establishes that the bilayer formation is a general phenomenon that is observable for a wide variety of synthetic amphiphiles.